feat: practice mode against mock bots

Tier-selectable practice page at /practice. Fights against classic
bots with dampened Elo. Routes to human fight page or arena based
on bot type.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/PracticePage.vue

@@ -0,0 +1,114 @@
+<script setup lang="ts">
+import { ref, computed, onMounted } from 'vue'
+import { useRouter } from 'vue-router'
+import { useNostr } from '../composables/useNostr'
+
+const router = useRouter()
+const { bot: myBot, isLoggedIn } = useNostr()
+
+const selectedTier = ref(0)
+const isStarting = ref(false)
+const error = ref('')
+
+const tiers = [
+  { value: 0, label: 'ROOKIE', desc: 'Easy challenges, forgiving scoring' },
+  { value: 1, label: 'BRONZE', desc: 'Moderate difficulty' },
+  { value: 2, label: 'SILVER', desc: 'Harder prompts, faster pace' },
+  { value: 3, label: 'GOLD', desc: 'Tough challenges, strict scoring' },
+  { value: 4, label: 'DIAMOND', desc: 'Expert difficulty' },
+  { value: 5, label: 'LEGEND', desc: 'Maximum difficulty' },
+]
+
+const tierColor = computed(() => {
+  const colors = ['text-text-muted', 'text-amber-600', 'text-gray-300', 'text-neon-gold', 'text-neon-cyan', 'text-neon-pink']
+  return colors[selectedTier.value] || 'text-text-muted'
+})
+
+onMounted(() => {
+  if (!isLoggedIn.value || !myBot.value) {
+    router.push('/register')
+  }
+})
+
+async function startPractice() {
+  if (!myBot.value || isStarting.value) return
+  isStarting.value = true
+  error.value = ''
+
+  try {
+    const res = await fetch(`/api/fights/practice/${myBot.value.id}`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+    })
+
+    if (!res.ok) {
+      const data = await res.json()
+      error.value = data.error || 'Failed to start practice fight'
+      return
+    }
+
+    const data = await res.json()
+    // Navigate to human fight page for the practice fight
+    if (myBot.value.isHuman) {
+      router.push(`/play/${data.fightId}`)
+    } else {
+      router.push(`/arena/${data.fightId}`)
+    }
+  } catch {
+    error.value = 'Network error'
+  } finally {
+    isStarting.value = false
+  }
+}
+</script>
+
+<template>
+  <div class="max-w-lg mx-auto px-4 py-8 space-y-6">
+    <h1 class="font-display font-black text-2xl text-neon-cyan tracking-wider">PRACTICE</h1>
+    <p class="font-mono text-sm text-text-muted">
+      Fight against training bots. No sats at stake.
+    </p>
+
+    <!-- Tier selection -->
+    <div class="space-y-2">
+      <h2 class="font-display font-bold text-sm text-text-secondary tracking-wider">DIFFICULTY</h2>
+      <div class="grid grid-cols-2 gap-2">
+        <button
+          v-for="tier in tiers"
+          :key="tier.value"
+          class="p-3 border-2 rounded text-left transition-all"
+          :class="selectedTier === tier.value
+            ? 'border-neon-cyan bg-neon-cyan/5'
+            : 'border-border hover:border-border/80'"
+          @click="selectedTier = tier.value"
+        >
+          <span class="font-display font-bold text-sm tracking-wider" :class="tierColor">
+            T{{ tier.value }}
+          </span>
+          <span class="font-display font-bold text-xs text-text-primary ml-2">{{ tier.label }}</span>
+          <p class="font-mono text-[10px] text-text-muted mt-0.5">{{ tier.desc }}</p>
+        </button>
+      </div>
+    </div>
+
+    <!-- Start button -->
+    <button
+      class="w-full min-h-[48px] py-4 bg-neon-green/10 border-2 border-neon-green text-neon-green
+             font-display font-black text-lg tracking-[0.15em] rounded
+             hover:bg-neon-green/20 transition-all
+             disabled:opacity-30 disabled:cursor-not-allowed"
+      :disabled="isStarting"
+      @click="startPractice"
+    >
+      {{ isStarting ? 'STARTING...' : 'START PRACTICE' }}
+    </button>
+
+    <div v-if="error" class="p-3 border-2 border-ko/30 bg-ko/5 text-center rounded">
+      <p class="font-mono text-xs text-ko">{{ error }}</p>
+    </div>
+
+    <p class="font-mono text-[10px] text-text-muted text-center">
+      Practice fights use dampened Elo (minimal rating impact)
+    </p>
+  </div>
+</template>

frontend/src/router.ts

@@ -81,6 +81,11 @@ const routes = [
     name: 'tournament',
     component: () => import('./pages/TournamentPage.vue'),
   },
+  {
+    path: '/practice',
+    name: 'practice',
+    component: () => import('./pages/PracticePage.vue'),
+  },
 ]
 
 export const router = createRouter({